Date: Fri, 22 May 2026 18:27:55 -0400 From: Mark Johnston <markj@freebsd.org> To: "Bjoern A. Zeeb" <bz@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 36b855f18925 - main - amd64/vmm: Lock global PCI passthrough structures Message-ID: <ahDYa6Y-gpvKt8ub@nuc> In-Reply-To: <21416977-p363-rs27-90n6-qq2o931r4ps5@mnoonqbm.arg> References: <69860b30.3f83f.acb567e@gitrepo.freebsd.org> <21416977-p363-rs27-90n6-qq2o931r4ps5@mnoonqbm.arg>
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On Fri, May 22, 2026 at 10:13:38PM +0000, Bjoern A. Zeeb wrote: > On Fri, 6 Feb 2026, Mark Johnston wrote: > > > The branch main has been updated by markj: > > > > URL: https://cgit.FreeBSD.org/src/commit/?id=36b855f1892575cbfe1cd5455b989bfc8ae07502 > > > > commit 36b855f1892575cbfe1cd5455b989bfc8ae07502 > > Author: Mark Johnston <markj@FreeBSD.org> > > AuthorDate: 2026-02-06 15:29:22 +0000 > > Commit: Mark Johnston <markj@FreeBSD.org> > > CommitDate: 2026-02-06 15:38:51 +0000 > > > > amd64/vmm: Lock global PCI passthrough structures > > > > There is a global list of ppt-claimed devices, accessed via several > > vmm ioctls. The ioctls are locked by per-VM locks, but this isn't > > sufficient to prevent multiple VMs from trying to bind a given device. > > > > Add a sleepable lock and use that to synchronize all access to ppt > > devices. > > > > Reviewed by: corvink, jhb > > MFC after: 2 weeks > > Differential Revision: https://reviews.freebsd.org/D55065 > > --- > > sys/amd64/vmm/io/ppt.c | 162 +++++++++++++++++++++++++++++++++---------------- > > 1 file changed, 111 insertions(+), 51 deletions(-) > > > > diff --git a/sys/amd64/vmm/io/ppt.c b/sys/amd64/vmm/io/ppt.c > > index 6feac5dcbbed..b522e18e3b24 100644 > > --- a/sys/amd64/vmm/io/ppt.c > > +++ b/sys/amd64/vmm/io/ppt.c > ... > > int > > @@ -529,10 +558,12 @@ ppt_unmap_mmio(struct vm *vm, int bus, int slot, int func, > > struct pptseg *seg; > > struct pptdev *ppt; > > > > + PPT_LOCK(); > > error = ppt_find(vm, bus, slot, func, &ppt); > > if (error) > > - return (error); > > + goto out; > > > > + error = ENOENT; > > for (i = 0; i < MAX_MMIOSEGS; i++) { > > seg = &ppt->mmio[i]; > > if (seg->gpa == gpa && seg->len == len) { > > @@ -541,9 +572,11 @@ ppt_unmap_mmio(struct vm *vm, int bus, int slot, int func, > > seg->gpa = 0; > > seg->len = 0; > > } > > - return (error); > > + break; > > } > > } > > +out: > > + PPT_UNLOCK(); > > return (ENOENT); > > } > > There's a bug here. That should be return (error). That's been breaking > pci passthru since February. I cannot imagine how no one noticed this in > 3 months? Fixed in commit b13335331092, thanks. If I'm reading the bhyve code correctly, this is "cosmetic": the libvmmapi wrapper for this operation is vm_unmap_pptdev_mmio(), called in bhyve's passthru_mmio_map(). When the ioctl fails, passthru_mmio_map() prints that warning and returns an error to the caller... and all callers ignore it. I think that was true even before my refactoring in commit 86150ed98b790. How exactly is passthru broken for you?home | help
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